Amateur Radio, Meteology and Astronomy website. JO10UX

Reception of ON0TVO on 10 GHz


By the calculations we know that we could expect about  -77,2 dbm on the entry of the antenna, so I wondered in how far the theoretical calculations would correspond to the practical measured signals.

My antenna is a 40 cm dish at about 7m height AGL and looking in the length direction of my street shoring my neighbors houses. At 500m I look between the roofs of some houses further on in the street.

The shack is just beneath the antenna so that I have only 10m of coax between the LNB and the sat tuner.


On the left you can see the schematic setup op the reception.

The antenna is a 40 cm dish with a modified Sat-TV LNB

To bring the signal down on 1.180 GHz I use Belden cable H125 having 23db attenuation pet 100m on 1.2 GHz. So the attenuation of the cable and the connectors until the splitter is +/- 3 db

The splitter is a 2x 3.5db one.

In the path to the spectrum analyzer there is a 10 db attenuator and counting an other 0.5db for the connectors between the spec.anal and the splitter.  So from the entry of the splitter, (the point normally connected to the sat tuner) I count an attenuation of 14 db.

 On the left one can see that the signal. The strength is fluctuating between -12dBm and -16dBm. On the right you can see in the upper level the signal level 1dBm (taken in account here the 14 dB attenuation) in the middle you can see the noise flour of -24dBm and the third value is difference. So we have a nice 25dB over the noice flour what result in an B5++ image.

Calculating back, assuming 0dBm on the splitter we have on the exit of the LNB 3dBm.

A MF gain of the LNB of 50 dB and an antenna gain of 30 db gives us -77 dBm  signal in the air.

So the calculated signal of -77.2 dBm seems to be correct what we messure.

سُوۡرَةُ حٰمٓ السجدة / فُصّلَت
ثُمَّ اسْتَوَىٰ إِلَى السَّمَاءِ وَهِيَ دُخَانٌ فَقَالَ لَهَا وَلِلْأَرْضِ ائْتِيَا طَوْعًا أَوْ كَرْهًا قَالَتَا أَتَيْنَا طَائِعِينَ ﴿١١
فَقَضَاهُنَّ سَبْعَ سَمَاوَاتٍ فِي يَوْمَيْنِ وَأَوْحَىٰ فِي كُلِّ سَمَاءٍ أَمْرَهَا ۚ وَزَيَّنَّا السَّمَاءَ الدُّنْيَا بِمَصَابِيحَ وَحِفْظًا ۚ ذَٰلِكَ تَقْدِيرُ الْعَزِيزِ الْعَلِيمِ ﴿١٢

Surah Fussilat: Thereafter turned He to the heaven and it was as smoke, and said Unto it and Unto the earth: come ye twain, willingly or loth. They said: we come willingly. (11) Then He decreed them as seven heavens in two days, and revealed Unto each heaven the command thereof; and We bedecked the nether heaven with lamps and placed therein a guard. That is the ordinance of the Mighty, the Knower. (12)

De hemelen en aarde (waren) een samenhangende massa. Wij hebben ze toen van elkaar gescheiden… Wij hebben de hemel tot een beschermend dak gemaakt … en de dag en de nacht, de zon en de maan geschapen. (Koran 41 11:12)

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